Massive stars may be the ultimate example of ‘live early and die young’. Unlike our own sun, which remains bright for billions of years, larger stars can run out of thermonuclear fuel in just a few million years before shedding their outer layers and exploding in dramatic supernovae. increase.
This week, NASA released a rare image of one such giant star, the Wolf-Rayet star, from the James Webb Space Telescope (JWST). Dubbed WR 124, the constellation is in the constellation Sagittarius, about 15,000 light-years away from Earth. The dying star, which is at least 30 times more massive than her Sun, is shrinking rapidly as it blows hot gas into the cold vacuum of space.
“We discovered it early,” says Anthony Moffat, a retired astrophysicist who had previously observed WR 124 using the Hubble Space Telescope and was not involved in the recent JWST measurements. explains. Moffat has been studying Wolf-Rayet stars for decades. “This is the youngest I know,” he says. The multicolored cloud in the image, somewhat misleadingly called a planetary nebula, is only a few thousand years old. Now, “the nebula hugs the stars,” he says. But as time goes on, the shells and rings of gas and dust expand and spread outward.
Stars are natural nuclear fusion reactors, glowing from the energy released by fusing hydrogen to form helium atoms. As massive stars burn up all their hydrogen, they begin to fuse helium into heavier elements through higher-energy nuclear fusion reactions that generate powerful stellar winds. Flowing at speeds in excess of 150,000 kilometers per hour, these winds carry the outer layers of the star and expel vast amounts of gas and dust into space.
This gas emits in the same kind of infrared light that the JWST detects. The astrophysicist combined data from two of his instruments at JWST, the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI), to create a spectacular image. The Hubble Space Telescope, which primarily collects light at optical wavelengths, has previously captured images of WR 124, but JWST’s observations show the star’s burgeoning nebula in stunning new detail.
“Personally, the most exciting part of this image is that it captures a rare event—a Wolf-Rayet star—with a level of detail that can only be achieved with JWST,” says Macarena García Marín. European Space Agency in collaboration with MIRI.
Only massive stars, not all stars, can experience Wolf-Rayet phases. Astronomers estimate he has only 1,000 Wolf-Rayet stars in our galaxy. The closest is in the Gamma Velorum system about 1,000 light-years away, visible from the Southern Hemisphere. The Wolf-Rayet star is a million times brighter than her in the Sun, says Moffat. “What they don’t have in numbers, they make up for in light,” he adds.
“That dust will spread out into space and eventually form planets,” NASA astrophysicist Amber Straugn said during a panel discussion at the 2023 South by Southwest Conference in Austin, Texas. He said where the image was first published: “I think it’s one of the most beautiful concepts in astronomy.”
But while we are all made of stardust, it seems that there is far more stardust in the universe than scientists can explain from a basic inventory of apparent sources. It’s always an interesting place for science when it disagrees with observations, and this is where we’re having the dust right now,” says Strawn. It helps scientists better understand this fundamental process when forging heavy elements and creating large amounts of dust.
Someday — thousands or even millions of years from now, but essentially on a galactic scale tomorrow — WR 124 will explode in a spectacular supernova explosion. In addition to the rich bounty of dust and heavy elements, the explosion could leave a black hole. Moffat speculates that the supernova remnant could instead stall as a neutron star. This is the final stop before a collapsing star reaches the ultimate oblivion of a black hole. For us, without a glimpse from an observatory that lingers in the distant future, we may never know what the outcome will be for WR 124. A generous gift of cosmic dust.
